Construction of Carbazoles from 2‐Bromobiaryls Using <scp> N ₂ </scp> as a N Source

Comprehensive Summary Due to the high activation barriers associated with cleaving both C–H bonds and the N≡N triple bond, achieving C–N bond formation from relatively inert C–H bonds as carbon sources under mild conditions has long posed a major challenge in synthetic chemistry. To address this long‐standing issue, we have developed a novel and straightforward approach for the synthesis of carbazoles, using N 2 as the nitrogen source and 2‐bromobiaryls as the carbon partner through an engineered one‐pot/two‐step protocol. The key to this protocol lies in the in‐situ generation of lithium nitride (Li 3 N) from N 2 using lithium as the reductant, which serves as a primary intermediate. This intermediate then undergoes a Pd‐catalyzed process involving successive C(sp 2 )–Br bond activation and intramolecular C(sp 2 )–H bond functionalization to form the target carbazole framework. Notably, this strategy exhibits a broad substrate scope, excellent tolerance towards various functional groups, and high regioselectivity. Leveraging this method, we have successfully synthesized a diverse range of high‐value carbazoles directly from N 2 , including biologically active natural alkaloids (such as the anti‐HIV drug Glycoborine and the antiviral compound Clausine V), optoelectronic materials ( e.g ., 11,12‐dihydroindolo[2,3‐ a ]carbazole), and 15 N‐labeled carbazoles. This approach not only expands the scope of carbon sources suitable for nitrogen incorporation from N 2 but also paves potential pathways for the development of diverse catalytic systems, offering new opportunities for the efficient synthesis of nitrogen‐containing heterocycles.